Insertion devices and method of use

ABSTRACT

This invention relates to devices, such as cannulas or needles, which are used for inserting expandable structures, such as medical balloons, into interior regions of a human or animal body, as well as methods for their use. In various embodiments, insertion devices described herein are capable of flaring at their tip to ease insertion and removal of expandable structures and reduce the risk of damaging such expandable structures during their insertion, inflation and removal. In other embodiments, insertion devices described herein are capable of directionally guiding and/or inhibiting expansion of an expandable structure within an interior region of an animal or human body to create optimally placed cavities for repair, augmentation and/or treatment of fractured and/or diseased bone.

FIELD OF THE INVENTION

[0001] This invention relates to an insertion device which is capable ofguiding expansion of an expandable structure towards or away from adesired direction and/or interior region of an animal or human body.This invention further relates to an insertion device for insertingexpandable structures, such as medical balloons, into an interior regionof a human or animal body, wherein the device is capable of expanding atthe tip. The present invention also relates to methods of using thedisclosed devices in the repair, augmentation and/or treatment offractured and/or diseased bone.

BACKGROUND OF THE INVENTION

[0002] Expandable structures, such as balloon dissectors and catheters,are used in various surgical procedures and for various rehabilitativepurposes in the medical arts. In angioplasty, balloon catheters arecommonly inserted into veins and arteries to expand blood vessels, mostcommonly to dilate and/or remove obstructions in the blood vessel (e.g.to remove constrictions blocking blood vessels which can cause a heartattack or stroke). Other types of surgical balloons have been used toaid surgeons in accessing specific organs during surgery, usually inlieu of previous insufflation techniques. Such balloons are commonlyinserted in a deflated state through an insertion device comprising acannula, catheter tube, or other similar device, and are positionedunder an organ. The balloon may then be inflated to lift and separate adesired organ away from surrounding organs and tissue to make sides ofthe desired organ easier to access during surgery. The balloon may alsobe placed and inflated so as to lift and separate other organs andtissues, leaving the desired organ for surgery exposed beneath.

[0003] Medical balloons have also been used during procedures forrepairing and/or reinforcing fractured and/or diseased bones. Somephysicians have used such balloons to create a working space adjacentfractured and/or diseased bone to allow the installation of plates,screws and/or other implantable articles to the bone. In this type ofprocedure, a cannula is generally inserted through an incision in theskin near the fracture area. A balloon is then inserted through thecannula and inflated between the bone and surrounding tissue around thefracture site to create a working space. A support plate and bonescrews, or other similar implements, can then be installed at thefracture site through small incisions in the skin. This type ofprocedure allows a surgeon to install implantable articles withouthaving to make a long skin incision to isolate and expose the bone.

[0004] More recently, balloons have been employed inside fracturedand/or diseased bones to repair, reinforce and/or treat the bone. Inthese procedures, balloons can be inserted through a cannula andinflated inside the bone, which can compact cancellous bone, create acavity and move cortical bone. The cavity can be filled with a suitablebone filler, such as bone cement (e.g., polymethylmethacrylate—PMMA),autograft or allograft tissue, or various other bone substitutes. Whenthe bone filler hardens, it essentially creates an internal “cast” whichallows the bone to heal properly, but also desirably allows the bone tobear weight immediately.

SUMMARY OF THE INVENTION

[0005] The present invention provides insertion devices which may beused with an expandable structure such as a balloon catheter to directthe expansion of the structure toward or away from a desired direction.Directed expansion of the expandable structure provides the physicianwith significant control over the compression of cancellous bone andcreation of cavities within the bone, as well as control over themovement of cortical bone. In addition, the controlled expansion of anexpandable structure allows the physician to tailor the shape anddimensions of the cavity, and the resulting shape and dimensions of thebolus of filler material contained therein. Moreover, directed expansionof an expandable structure permits a physician to minimize disruption ofhealthy cancellous and/or cortical bone during a treatment procedure,thereby further enhancing healing of the bone after treatment.Accordingly, the devices and methods disclosed herein permit thephysician to optimize the ability of the bone to withstand compressiveforces and/or heal as quickly as possible after the procedure iscompleted.

[0006] Expandable structures such as balloon catheters and dissectorsare typically formed in spherical or elliptical shapes, and normallyexpand substantially outward. These balloons are desirably fairlylow-profile such that they can fit through a cannula. Once insertedthrough the cannula into the region of treatment, such balloons willgenerally inflate fairly symmetrically about the axis of the cannula orother insertion device. However, as discussed in U.S. Pat. No.5,972,015, which is incorporated by reference herein, inflation of aballoon about the cannula's axis can be undesirable in some situations.To account for these situations, various alternative balloon designs andexpansion constraint arrangements have been proposed, such as thosedescribed in the '015 patent.

[0007] The inventions disclosed herein further permit a practitioner toutilize a wide variety of expandable structures in conjunction with themethods and devices disclosed herein. Because the cannula or otherinsertion device substantially guides the direction of expansion of theexpandable structure, there is less need to incorporate expansionconstraints in the expandable structure itself. In addition, if theinsertion device is comprised of a radiopaque material, the orientationof the device itself can be visualized during the surgical procedureunder x-ray fluoroscopy, allowing the practitioner to visually verifythe direction of expansion of the structure throughout the entireprocedure. Of course, it should be understood that the devices andmethods of the present invention could also be used in conjunction withexpandable structures incorporating various expansion restraintarrangements.

[0008] In a general embodiment of the present invention, an insertiondevice comprises a hollow member, which is preferably cylindrical, witha distal end and a proximal end, wherein the distal end is the tip, orpoint of insertion, of the insertion device. The distal end of thehollow member desirably comprises a platform which constrains expansionof the expandable structure in one or more directions, but permits theexpandable structure to expand in non-constrained directions. In effect,the platform of the hollow member acts as a support or foundationagainst which the expandable structure pushes as it expands. Desirably,the supporting action of the platform induces the expandable structureto expand away from the platform, allowing the practitioner to directexpansion towards and/or away from a desired region.

[0009] In another general embodiment, the platform comprises a platformor expansion guide which is inserted through a hollow member of aninsertion device, the guide desirably extending distally past the tip ofthe hollow member and into a bone. The guide will desirably act as asupport or foundation against which the expandable structure expands,inducing the structure to expand away from the guide. Because thisembodiment of the guide travels through the hollow member, and need notinitially penetrate soft tissues and/or the harder cortical bone, theguide design can be optimized to provide maximum support for theexpandable structure.

[0010] In another general embodiment of the present invention, aninsertion device comprises a hollow member with a distal end and aproximal end, wherein the distal end is the tip, or point of insertion,of the insertion device. The distal end of the hollow member desirablycomprises a platform which directs the expansion of the expandablestructure in one or more directions. The distal end of the hollow memberfurther comprises one or more crease or fold lines along which at leasta portion of the platform desirably deforms after insertion into a bone.By deforming along predetermined lines, sharp surfaces on the platformare desirably moved away from the expandable structure. In addition,bending of the platform can significantly affect the surface area of theplatform in contact with the expandable structure as well as thestrength and resistance to deformation of the platform. After theexpandable structure is contracted, the platform can be withdrawnthrough the cannula, with the distal end of the insertion devicedesirably bending the platform towards a lower-profile shape forremoval.

[0011] In another general embodiment of the present invention, theinsertion device comprises a hollow member having a plurality of scorelines spaced about the circumference of the distal tip, these scorelines desirably forming a plurality of adjacent sections oriented in afirst, lower profile orientation. After inserted to a desired locationwithin the vertebral body, the adjacent sections can be expanded outwardto a second orientation, where the adjacent sections substantially forma funnel, cone or flare at the tip of the insertion device. When removalof the expandable structure is desired, the flared tip desirably guidesthe expandable structure into the cannula, facilitating passage of theexpandable structure into and through the cannula. If desired, theadjacent sections can further incorporate one or more guides or ribswhich desirably impinge upon the expandable structure, folding and/ortwisting the expandable structure along desired lines and/or in adesired manner, further facilitating removal of the expandable structurethrough the cannula. When removal of the insertion device from thevertebral body is desired, the withdrawal of the insertion devicethrough the harder cortical bone desirably bends the adjacent sectionsback towards and/or into their first, lower profile orientation.

[0012] The present invention is further related to methods for using thedisclosed devices for repair, augmentation and/or treatment of fracturedand/or diseased bones. One embodiment of an insertion device constructedin accordance with the teachings of the present invention is insertedthrough cortical bone and into cancellous bone in a vertebral body of apatient. The insertion device is positioned such that the platformdirects the expansion of an expandable structure towards a section ofcortical bone to be moved to a desired position, such as a depressedupper or lower plate of a vertebral body. The expandable structure isexpanded against the platform, which desirably induces the expandablestructure to expand substantially away from the platform, compressingcancellous bone to form a cavity and moving the targeted section ofcortical body towards a desired position. The expandable structure iscontracted, and the cavity is then filled with an appropriate bonefiller material. This method, which permits manipulation of corticalbone with a minimum of cancellous bone compression, allows apractitioner to move targeted cortical bone while preserving much of thecancellous bone in an uncompressed state. In addition, this methodpermits the practitioner to maximize the force which the expandablestructure exerts on the cortical bone.

[0013] In another embodiment of the present invention, an insertiondevice constructed in accordance with the teachings of the presentinvention is inserted into cancellous bone in a vertebral body of apatient. The insertion device is positioned such that the platformdirects the expansion of an expandable structure towards a section ofcancellous bone to be compressed. The expandable structure is expanded,which desirably compresses some or all of the targeted cancellous bone,creating a cavity within the cancellous bone. The expandable structureis contracted and, if desired, the insertion device is repositioned suchthat the platform directs the expansion of an expandable structuretowards another section of cancellous bone to be compressed. Theexpandable structure is expanded, compressing some or all of thetargeted cancellous bone and increasing the size and/or altering theshape of the cavity within the bone. If desired, the procedure can berepeated to create a cavity of desired dimensions. The cavity is thenfilled with an appropriate bone filler material. This method, whichfacilitates the creation of large cavities within the bone, allows thepractitioner to tailor the cavity shape/size to optimize thepost-treatment strength and/or healing of the bone. Similarly, thedisclosed method can be used to reposition cortical bone towards adesired position, permitting a practitioner to gradually displace smallor large sections of the cortical bone, at the practitioner's option.

[0014] In another embodiment, the disclosed devices and methodsfacilitate a practitioner's ability to repair, reinforce and/or treattargeted bone regions in situations where the insertion device isinitially positioned near a cortical bone wall of a targeted boneregion. Because the disclosed devices and methods provide substantialcontrol over the direction of expansion of the expandable structure, thepractitioner can position and/or reposition the platform to shield thenearby cortical bone from some or all of the expandable structure duringsome or all of the surgical procedure. Depending upon the orientation ofthe platform, the structure can be expanded to differing dimensions,desirably maximizing compression of cancellous bone and/or movement ofcortical bone at each orientation. Accordingly, there is no need toreorient the entire insertion device to accomplish the objectives of theprocedure, which desirably eliminates a source of additional traumaoccurring during the procedure.

[0015] In another embodiment, an insertion device is inserted throughcortical bone and into cancellous bone in a vertebral body of a patient.A stylet in the insertion device is removed, causing the distal end ofthe hollow member of the insertion device to expand or flare. Anexpandable structure is inserted through the insertion device into thevertebra, is expanded to create a cavity, and is contracted and removedthrough the insertion device. As the expandable structure is withdrawnthrough the insertion device, the flared distal end of the insertiondevice desirably guides the structure into the insertion device. Thecavity is then filled with an appropriate bone filler.

[0016] Other objects, advantages and embodiments of the invention areset forth in part in the description which follows, and in part, will beobvious from this description, or may be learned from the practice ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a coronal view of a vertebral body, showing a cannulainserted in a vertebral body, with a spherical expandable structureexpanded within the vertebral body;

[0018]FIG. 2 is a coronal view of a vertebral body, showing oneembodiment of an insertion device constructed in accordance with theteachings of the present invention which has been inserted into avertebral body, with an expandable structure expanded within thevertebral body;

[0019]FIG. 3a is a side view of an alternate embodiment of an insertiondevice constructed in accordance with the teachings of the presentinvention, wherein the distal end of the hollow member comprises one ormore longitudinal score lines at its circumference.

[0020]FIG. 3b is a cross-sectional side view of the insertion device ofFIG. 3a, showing the adjacent sections in a lower profile orientation;

[0021]FIG. 4 is a side view of the insertion device of FIG. 3a, showingthe adjacent sections in a deployed or flared position;

[0022]FIG. 5 is a cross-sectional side view of the insertion device ofFIG. 3a, with a stylet positioned within the hollow member of thedevice;

[0023]FIG. 6 is an end of the insertion device of FIG. 4;

[0024]FIG. 7 is a side view of another alternate embodiment of aninsertion device constructed in accordance with the teachings of thepresent invention, the device comprising an extension or platformextending from the distal end of the device;

[0025]FIG. 8 is a top plan view of another alternate embodiment of aninsertion device constructed in accordance with the teachings of thepresent invention, showing a crease line extending along a platform ofthe device;

[0026]FIG. 9a is a side view of another alternate embodiment of aninsertion device constructed in accordance with the teachings of thepresent invention with a stylet positioned within the lumen of thedevice;

[0027]FIG. 9b is a cross sectional side view of the insertion device ofFIG. 9a, showing the adjacent sections in a lower profile orientation;

[0028]FIG. 9c is a side view of the insertion device of FIG. 9a, showingthe adjacent sections moved to a deployed position as the stylet iswithdrawn from the device;

[0029]FIG. 10 is an end view of another alternate embodiment of aninsertion device constructed in accordance with an alternate embodimentof the present invention;

[0030]FIG. 11 is a side view of the insertion device of FIG. 10.

[0031]FIG. 12 is a side view of the insertion device of FIG. 10, with astylet positioned within the hollow member of the device;

[0032]FIG. 13 is a side view of an alternate embodiment of an insertiondevice constructed in accordance with the teachings of the presentinvention, with a stylet positioned within the hollow member of thedevice;

[0033]FIG. 14 is a side view of one embodiment of a stylet constructedin accordance with the teachings of the present invention, for use withvarious embodiments of the insertion device of the present invention;

[0034]FIG. 15 is a side view of an alternate embodiment of a styletconstructed in accordance with the teachings of the present invention,for use with alternate embodiments of the insertion device of thepresent invention;

[0035]FIG. 16a is a cross sectional side view of an alternate embodimentof an insertion device and stylet constructed in accordance with theteachings of the present invention, showing one method of assembling thedevice and stylet;

[0036]FIG. 16b is a cross section side view of the insertion device andstylet of FIG. 16a, showing the stylet inserted fully into the hollowmember of the device during assembly;

[0037]FIG. 17 is a cross sectional side view of the insertion device andstylet of FIG. 16b, with the adjacent sections of the device positionedin a lower profile orientation around the stylet;

[0038]FIG. 18 depicts a patient about to undergo a surgical procedure inaccordance with the teachings of the present invention;

[0039]FIG. 19 depicts an incision point and underlying vertebrae for thepatient of FIG. 18;

[0040]FIG. 20 is a corona view of a vertebra showing an insertion deviceapproaching the posterior side of the vertebral body;

[0041]FIG. 21a depicts an insertion device penetrating the vertebralbody of FIG. 20;

[0042]FIG. 21b is a coronal view of the vertebra of FIG. 20, with aninsertion device positioned within the cancellous bone;

[0043]FIG. 22 is a coronal view the vertebra body of FIG. 21a, with theadjacent sections positioned in a deployed orientation.

[0044]FIG. 23 is a coronal view of the vertebra body of FIG. 22, whereinan expandable structure is expanded within the vertebra;

[0045]FIG. 24 is a coronal view of a vertebra showing an insertiondevice comprising a platform within the vertebra, and an expandablestructure expanding away from the platform of the insertion device;

[0046]FIG. 25 is a coronal view of the vertebra of FIG. 24, wherein theexpandable structure has been contracted, the device rotated, and anexpandable structure expanded towards another region of the vertebra;

[0047]FIG. 26 is a coronal view of the vertebra of FIG. 24, wherein thecreated cavity is filled with a bone filler;

[0048]FIG. 27 is a coronal view of the vertebra of FIG. 24, wherein anexpandable structure and insertion device are used to enlarge a firstcavity which has been partially filled with a bone filler;

[0049]FIG. 28 are side and perspective views of various embodiments ofplatforms constructed in accordance with the teachings of the presentinvention;

[0050]FIG. 29 is a side perspective view of one embodiment of anexpansion guide constructed in accordance with the teachings of thepresent invention;

[0051]FIG. 30 is a partial side perspective view of the expansion guideof FIG. 29 inserted into an insertion device;

[0052]FIG. 31 is a side view of another alternate embodiment of aninsertion device constructed in accordance with an alternate embodimentof the present invention;

[0053]FIG. 32 is a cross-sectional view of the insertion device of FIG.31, taken along line 32-32;

[0054]FIG. 33 is a cross-sectional view of the insertion device of FIG.31, taken along line 33-33;

[0055]FIG. 34 is a side view of another alternate embodiment of aninsertion device constructed in accordance with an alternate embodimentof the present invention;

[0056]FIG. 35 is a cross-sectional view of the insertion device of FIG.34, taken along line 35-35;

[0057]FIG. 36 is a cross-sectional view of the insertion device of FIG.34, taken along line 36-36;

[0058]FIG. 37 is a cross-sectional view of a step in one method ofmanufacturing the insertion device of FIG. 34, taken along line 36-36;

[0059]FIG. 38 is a cross-sectional view of the insertion device of FIG.37, during a subsequent manufacturing step;

[0060]FIG. 39 is a cross-sectional view of the insertion device of FIG.37, during a subsequent manufacturing step.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0061] The present invention overcomes the problems and disadvantagesassociated with current strategies and designs in insertion devices foruse with expandable structures, such as medical balloons. In particular,the present invention provides insertion devices which may be used withexpandable structures to direct expansion of the structure as well as toassist in insertion and removal of expandable structures from aninterior region of a human or animal body. The methods and instrumentssuitable for such treatment are more fully described in U.S. Pat. Nos.4,969,888, 5,108,404, 5,827,289, 5,972,015, 6,048,346 and 6,066,154,each of which are incorporated herein by reference.

[0062]FIG. 1 depicts a vertebra 41 to be treated using an expandablestructure 310. An insertion device 70, such as a cannula or spinalneedle, extends through the cortical bone 69 of the vertebra 41, andinto the cancellous bone 71. An expandable structure 310 is introducedinto the vertebra 41 through the insertion device 70, and desirablyexpands within the cancellous bone 71, typically expanding outward in aspherical, cylindrical or other manner thereby creating a cavity. Toavoid contacting the cortical bone 69 during expansion of the structure310, a practitioner will typically position the insertion device 70 asufficient distance away from the cortical bone 69 to allow room for thestructure 310 to expand outward. However, if the insertion device 70 ispositioned too close to the cortical bone 69, if the structure expands agreater amount towards the cortical bone 69 (such a where the cancellousbone is weaker in that direction), or if the intervening anatomyseverely constrains placement of the insertion device to locations nearthe cortical bone 69, the expansion of the structure and cavity creationmay be less than optimal.

[0063]FIGS. 2 and 7 depict one embodiment of an insertion deviceconstructed in accordance with the teachings of the present invention.The insertion device comprises a hollow member 210 which may be anyappropriate shape, but is preferably cylindrical. The hollow member 210has a distal end 250 and a proximal end 255, wherein the distal end 250is the tip, or point of insertion, of the insertion device. The hollowmember 210 may be any appropriate length to allow the insertion deviceto provide percutaneous access to an interior region of a body requiringtreatment. In one preferred embodiment, the hollow member 210 isapproximately 12 cm long.

[0064] The hollow member 210 has an appropriate central bore diameterand wall thickness to allow surgical instruments and/or medicalmaterials to be passed therethrough, while desirably being strong enoughto resist deformation during insertion into an interior region of a bodysuch as a bone. In a preferred embodiment, the hollow member 210 has aninternal bore diameter of 0.3 cm and a wall thickness of 0.05 cm. Thehollow member 210 may further be made of any material which isappropriate for use within a human or animal body including, but notlimited to, stainless surgical steel, teflon, polyethylene,polypropylene, silicates, and liquid crystal polymers (as described inU.S. Pat. No. 6,036,711, which is incorporated herein by reference). Inone preferred embodiment, the hollow member 210 is made of stainlesssteel. If desired, the hollow member 210 may further be coated with anyappropriate medical grade coating including, but not limited to, ananti-infective, an anticoagulant, a release coating, and/or a slippingagent.

[0065] In one embodiment, an extension or platform 220 protrudes fromthe distal end 250 of the hollow member 210. In this embodiment, theplatform 220 comprises a semi-cylindrical section which extends from thewalls of the hollow member 210. Of course, the platform could be formedin many different configurations, including one or more of those shownin FIG. 28. In one preferred embodiment, the platform 220 is made of thesame material as the hollow member 210. Of course, it should beunderstood that the platform 220 could be formed of and/or coated withmaterials different from those incorporated into the hollow member 210.In addition, the platform 220 could be formed integrally with the hollowmember 210, such as by cutting away a portion of the hollow member 210near the distal tip 250 and leaving a cradle shape, or by attaching theplatform 220 to the distal tip 250 of the hollow member by various meanswell known in the art such as welding, adhesive bonding, etc. In oneembodiment, the platform 220 will have sufficient column strength suchthat it will not buckle and/or significantly deform as the insertiondevice is introduced through soft tissue and/or the bone. In thedisclosed embodiment, the portion of the distal tip 250 of the hollowmember 210 has been longitudinally bisected and removed, with theremaining semi-cylindrical section comprising the platform 220.

[0066] Desirably, the platform 220 will be positioned near theexpandable structure 310 prior to expansion, with the platform 220located between the expandable structure 310 and a region within thevertebra 41 which is not to be compressed or affected. As the structure310 expands, the platform 220 will act as a support, foundation orbarrier to the expandable structure 310, inhibiting the structure 310from expanding in one or more directions. In effect, the platform 220will induce the expandable structure 310 to expand away from theplatform 220. Because the insertion device and platform 220 aresubstantially secured within the cortical bone, the platform 220 willdesirably remain substantially rigid and/or immobile within the vertebraas the structure expands. This arrangement allows a practitioner todirect the expansion of the expandable structure 310 towards or awayfrom a specific region of the vertebra.

[0067] In another embodiment, best shown in FIG. 8, the platform 220comprises at least one longitudinal crease line 225, preferably locatednear the center of the platform, along which at least a portion of theplatform 220 desirably deforms prior to, during or after expansion ofthe structure 310. By causing the platform 220 to deform in a controlledmanner, this embodiment facilitates introduction of the platform in alower profile condition, permits the platform to deform to a larger areato best direct the expansion of the structure, and then allows theplatform to be withdrawn in a lower profile condition. As an expandablestructure 310 is expanded, thereby exerting pressure against theplatform 220, the crease line 225 facilitates flattening of the platform220 in a controlled manner, thereby providing a widened and improvedsupport surface for guiding expansion of the expandable structure 310.Flattening of the support 220 can also deform outward the edges of theplatform 220, which may be sharp, thereby reducing the risk of damagingor rupturing the expandable structure 310. The crease lines 225 may becreated by mechanical cutting, laser etching, welding, brazing, or anyother well known means.

[0068] In an alternate embodiment, the crease line 225 could reinforcethe platform 220, minimizing deformation of the platform 220 duringexpansion of the structure 220. For example, the rounded underside ofthe platform 220 could be crimped or bent along the longitudinal axis ofthe platform to stiffen the platform 220 and resist deformation of thistype. If desired, the crimp (not shown) could parallel one or morecrease lines 225. In an alternate embodiment, a crimp (not shown) whichextends approximately 7 mm proximally from the distal tip of theplatform 220 results in a significant increase in the resistance of theplatform 220 to displacement and/or deformation.

[0069] In another alternative embodiment, the distal tip of the platformincorporates one or more serrations or teeth which extend outward fromthe distal tip and facilitate anchoring of the platform into theopposing cortical wall of the targeted bone region. This arrangement,which allows the platform to be supported at both ends, significantlyincreases the resistance of the platform to displacement and/ordeformation during expansion of the expandable structure.

[0070] In another embodiment, best shown in FIGS. 11, 12 and 13, theplatform 220 comprises a relatively flat section extending from thedistal end 250 of the hollow member 210. In a preferred embodiment, theplatform 220 can incorporate a flattened top surface 212 and a curvedouter surface 213, the curved outer surface 213 being formed integrallywith the hollow member 210. Although this embodiment slightly constrictsthe inside bore of the hollow member 210, the shape and increasedthickness of the platform 220 greatly increase the amount of force theplatform 220 can withstand without deforming. In addition, thisembodiment minimizes impingement of sharp edges onto the expandablestructure. Moreover, the flat and thickened platform 220, as shown inFIG. 13, can be shaped to have a sharpened tip so that the platform 220can easily pass through soft tissue and/or bone. In an alternateembodiment, a flexible and/or pliable surface (not shown) may bepositioned between the expandable structure and/or the platform, or maybe incorporated into the platform or expandable structure, to minimizetearing, cutting and/or other failure of the expandable structure.

[0071]FIGS. 29 and 30 depict an alternate embodiment of an insertiondevice and associated component constructed in accordance with theteachings of the present invention. In this embodiment, the insertiondevice or cannula comprises a hollow member 210 which may be anyappropriate shape, but is preferably cylindrical. The hollow member 210has a distal end 250, wherein the distal end 250 is the tip, or point ofinsertion, of the insertion device. An expansion guide 400, best shownin FIG. 29, comprises a handle assembly 405 and a guide shaft 410. Theguide shaft 410 is desirably longer than hollow member 210, and is alsodesirably sized to pass through the lumen of the hollow member 210. Inthe disclosed embodiment, an upper surface 420 of the guide shaft 410 isdesirably substantially flattened, and a lower surface 415 of the guideshaft is curved. If desired, the handle assembly 405 and/or guide shaft410 can incorporate one or more alignment marks 407 to indicate theorientation of the guide shaft, as well as the amount the guide shaftextends from the distal end 250 of the hollow member. In addition, thehandle assembly may incorporate mechanical connectors or clips (notshown) to secure the expansion guide 400 to the hollow member 210.

[0072] In this embodiment, after an insertion device is positionedwithin a targeted vertebral body, the expansion guide 400 can bepositioned near an expandable structure (not shown) prior to expansion,with the guide shaft 410 located between the expandable structure and anarea of the cancellous bone where compression of the cancellous bone isnot desired. If desired, the expandable structure can be introducedthrough the insertion device before the expansion guide 400 isintroduced through the insertion device. As the structure expands, theguide shaft 410 will act as a support, foundation or barrier to theexpandable structure, desirably inhibiting the structure from expandingin one or more directions. In effect, the guide shaft 410 will actsimilar to the platform 220 previously described, and will induce theexpandable structure 310 to expand away from the guide shaft 410. Thisarrangement allows a practitioner to direct the expansion of theexpandable structure towards or away from a specific region of thevertebral body. In addition, because the expansion guide 400 can beinserted to varying depths within the hollow member, the practitionercan choose the desired length of the guide shaft 410 to extend out ofthe insertion device. In an alternate embodiment, if desired a pluralityof platforms (not shown) can be used to shield multiple directions.

[0073] Because the expansion guide 400 may be introduced after theinsertion device is already positioned within the targeted vertebralbody, the expansion guide 400 need not have sufficient column strengthto penetrate soft tissue and/or cortical bone. This allows the expansionguide 400 to assume a variety of cross sectional forms, including one ormore of the forms shown in FIG. 28.

[0074] In another alternate embodiment of an insertion deviceconstructed in accordance with the teachings of the present invention,best shown in FIGS. 3a, 4 and 6, the insertion device comprises acylindrical hollow member 210 having a distal end 250 and a proximal end255, wherein the distal end 250 is the tip, or point of insertion, ofthe insertion device. The distal end 250 of the hollow member 210 isscored longitudinally to form a plurality of score lines 260 around thecircumference of the hollow member 210. The plurality of score lines 260may run parallel or at an angle to one another, and are separated byadjacent sections 265. The score lines 260 may be of any appropriatelength and depth to allow the distal end 250 to flare (See FIGS. 4 and6) when an outward pressure is exerted upon the adjacent sections 265.

[0075] In one preferred embodiment, the score lines 260 extendapproximately 0.5 cm along the longitudinal axis of the hollow member210, and extend through the wall of the hollow member 210. The scorelines 260 are cut into the distal end 250 using any appropriatetechnique known to those of skill in the art including, but not limitedto, laser cutting or etching, chemical etching and/or mechanical cuttingwith carbide or diamond tip saws or high pressure water. The distal end250 of the hollow member 210 will desirably comprise a sufficient numberof longitudinal score lines 260 to allow ease of flaring of the distalend 250. The quantity of score lines 260 required for appropriateflaring is determined by the diameter and wall thickness of the hollowmember 210 and the ductility of the material. In one embodiment of thepresent invention, the hollow member 210 comprises at least three scorelines 260 in the distal end 250. In another embodiment, best shown inFIG. 6, the hollow member 210 comprises six score lines 260 in thedistal end 250.

[0076] The flaring of the tip of the hollow member 210 may easeinsertion and removal of an expandable structure, such as a medicalballoon. By flaring the tip, the sharp outer edges of the hollow member210 are pushed away from the expandable structure and into thesurrounding cancellous bone. The expandable structure is thus isolatedfrom these sharp edges, which could contact the expandable structureduring expansion, possibly causing the structure to rupture or tear.During withdrawal of the expandable structure, the larger diameter ofthe flared tip will desirably guide the expandable structure into thesmaller diameter hollow member 210, easing withdrawal of the expandablestructure into and through the hollow member 210.

[0077] If desired, flaring of the tip can be accomplished using anexpandable structure to provide a desired outward force, or the tip canbe flared mechanically. For example, in the embodiment shown in FIG. 3b,the adjacent sections 265 are thickened on their internal surfaces toform one or more protrusions 266 extending inward from each adjacentsection 265. If desired, the protrusions 266 could be formed as a singlecontinuous thicker area of the circumference of distal end 250,interrupted by the longitudinal score lines 260. When a tool, such as ablunt obturator, boring member or stylet 275, which is described below,slides across or presses against the protrusions 266, the adjacentsections 265 are desirably forced outward, flaring the distal end 250 ofthe hollow member 210 in the desired manner.

[0078] The insertion device of the present invention may furthercomprise a removable blunt obturator or stylet 275. See FIGS. 5, 9a, 9b, 12, and 17. The stylet 275 comprises a distal end 279 having a tip276 which can be blunt or sharpened. If desired, the stylet can becannulated (not shown) to accommodate the guide wire of a spinal needleassembly, as well known in the art. In one embodiment of the presentinvention, best shown in FIGS. 15, 16a and 17, the tip 276 of the stylet275 will desirably extend from the distal end 250 of the hollow member210 when the insertion device is assembled for insertion into aninterior body region. The stylet 275 desirably pushes and/or cuts atunnel or passageway through soft tissue and bone to permit placement ofthe insertion device into the desired interior body region. If desired,the stylet 275 can further comprise a mating end (not shown) whichallows the boring member 275 to be mated to the insertion device duringthe insertion procedure, in a manner well known in the art. Mating ofthe hollow member 210 to the stylet 275 desirably prevents slippage andrelative movement between these devices during insertion into thepatient. The stylet 275 is preferably mated to the hollow member 210 ina manner which allows for easy removal of the stylet 275 from the hollowmember 210 after placement of the insertion device in the targeted area.

[0079] The stylet 275 may be made of any appropriate medical gradematerial and is preferably made of the same material as the hollowmember 210. In one preferred embodiment, the stylet 275 is made ofstainless steel. The stylet 275 may further be any appropriate shape andsize which allows it to slide within and mate with the hollow member210. In a preferred embodiment, the stylet 275 is approximately the samecylindrical shape as the hollow member 210, is slightly longer than thehollow member 210 so that the tip 276 will protrude from the distal end250 of the hollow member 210 when assembled for insertion, and isslightly smaller in diameter than the inner bore diameter of the hollowmember 210, such that the stylet 275 can freely slide within the hollowmember 210 for easy insertion and withdrawal.

[0080] In one embodiment of the present invention, shown in FIGS. 15,16a, 16 b and 17, the distal end 279 of the stylet 275 desirablycomprises one or more grooves or divots 273 located near the tip 276. Ina preferred embodiment, the divot 273 is a continuous divot whichencircles the circumference of the distal end 279 of the stylet 275. Astylet 275 having at least one divot 273 at the distal end 279 is wellsuited to mate with a hollow member 210 having a plurality oflongitudinal score lines 260 and one or more protrusions 266 on eachadjacent section 265 in its distal end 250, as depicted in FIGS. 3b, 5,and 17. When such an insertion device is assembled, the stylet 275 canbe inserted into the hollow member 210 until the distal end 279 extendsout of the hollow member 210. The adjacent sections 265 are then foldedor crimped inwards, with the protrusions 266 extending into the divot273 in the stylet 275, such that the outer wall of hollow member 210 isrelatively cylindrical prior to insertion of the insertion device. Oncethe insertion device is in place within the desired interior region of abody, the stylet 275 is pulled out of the hollow member 210, flaring theone or more protrusions 266 and forcing the distal end 279 of the stylet275 outward. In another embodiment, the collar section 267 adjacent toone or more protrusions 266 is thinner than the rest of the wall ofhollow member 210 to make flaring of the distal end 250 easier.

[0081] In another embodiment of an insertion device constructed inaccordance with the teachings of the present invention, best depicted inFIGS. 9a through 9 c, an insertion device comprises a hollow member 210having a platform 220 and one or more adjacent sections separated by aplurality of longitudinal score lines 260 at the distal end 250. Inanother embodiment, this type of insertion device further comprises astylet 275 which has at least one divot 273 located near the tip 276.The stylet 275 can be used to exert outward pressure on one or moreprotrusions 266 on adjacent sections 265 causing the distal end 250 toflare out near the platform 220. Such a preferred embodiment of aninsertion device of the present invention allows a user to directexpansion of an expandable structure, such as a medical balloon, whileeasing insertion and removal of the expandable structure and reducingthe risk of damage to the expandable structure.

[0082] The present invention further provides methods for using thedisclosed insertion devices to direct expansion of the expandablestructure and/or to simplify insertion and removal of an expandablestructure from an interior region of a human or animal body. Forillustrative purposes, a method for osteoporotic vertebral fixation,i.e. insertion and expansion in a vertebral body, will be described.However, a similar method may be used within any appropriate region of ahuman or animal body.

[0083] As shown in FIGS. 18-27, in one embodiment of the presentinvention, a patient 10 is placed onto a holder 15, generally U shaped,so that the patient's back is exposed. An x-ray, CAT-scan, MRI,fluoroscope, or other appropriate device 20 which permits a practitionerto visualize the insertion and placement of an insertion device duringthe surgical procedure may be positioned around the patient. Aninsertion device 200 comprising a hollow member 210 fitted with a stylet275, as previously described above, can be introduced through the softtissues to a vertebral body, which can located fluoroscopically. Thestylet and insertion device will desirably penetrate through thecortical bone 31 of the vertebral body 30, and the stylet 275 can thenbe removed. In an embodiment of the insertion device wherein the hollowmember 210 comprises one or more adjacent sections 265 separated by aplurality of longitudinal score lines 260, the removal of the stylet 275desirably causes the distal end 250 of the hollow member 210 to flare asdepicted in FIG. 22.

[0084] An expandable structure 50, such as a medical balloon, can beinserted through the hollow member 210 into the vertebral body 30.Placement of the expandable structure 50 can be monitored by anyappropriate means, including x-ray fluoroscopy or real time MRI. Thestructure is expanded, creating a cavity 55 within the cancellous bone32 and/or moving cortical bone 31, and then contracted. In an embodimentwhere the distal end 250 of the hollow member 210 has been flared, theflared end guides the structure 50 into the hollow member 210. Thecavity 55 can then be filled with an appropriate bone filler 60.

[0085] In another preferred embodiment of the present invention, thehollow member 210 comprises a platform 220 extending from the distal end250. See FIGS. 24 through 27. Once the hollow member 210 is introducedinto the vertebral body 30, the hollow member can be rotated until theplatform 220 shields an area of the vertebral body where expansion ofthe structure 50 is undesired. When the structure 50 is expanded, theplatform 220 induces the structure 50 to expand away from the platform220. In this way, an appropriate area for a cavity may be formedgenerally irrespectively of where the insertion device is placed withinthe vertebral body. Thus, if the insertion device is placed in aposition within the vertebral body that is not optimal for cavityformation, instead of torquing, bending, or otherwise adjusting theplacement of the entire insertion device, the insertion device 200 maysimply be rotated until the platform 220 faces a desired direction ofcavity formation. An indicator (not shown) on the handle or proximalportion of the hollow member 210 will desirably indicate to thepractitioner the orientation of the platform within the bone. Similarly,if a larger or asymmetrical cavity is desired, after a first cavity isformed by expanding the structure 50, the structure 50 may becontracted, the insertion device 200 may be rotated until the platform220 faces another direction, and the same or a different structure 50may be expanded to form a second cavity, etc., as depicted in FIG. 25.Any desired number and/or dimension of cavities may be formed in thisway. In another embodiment, different shaped balloons may be inserted toform each different cavity or multiple expandable structures of varyingshapes may be used to form each cavity.

[0086] When the desired cavity or cavities 55 have been formed, theexpandable structure 50 may be contracted and removed through the hollowmember 210. In an embodiment wherein the distal end 250 of the hollowmember 210 is flared, removal of the contracted structure may be easierbecause the flared tip guides the structure into the hollow member 210.A suitable bone substitute, such as polymethylmethacrylate bone cement,a two-part polyurethane material, or any other appropriate bone filler60, is injected into the cavity 55 or cavities formed. In oneembodiment, a first cavity 55 may be formed and, if desired, at leastpartially filled with a bone filler 60, then the same or a differentexpandable structure 50 may be inserted and expanded in the same cavity55, thereby compacting the hardening bone filler and/or more cancellousbone 32, and the cavity 55 may then be further filled with the same or adifferent bone filler 60. In another embodiment, a first cavity 55 maybe formed, an insertion device 200 with a platform 220 may then berotated and the same or a different expandable structure 50 may beinserted to create a second cavity or enlarge the first cavity 55, andthe cavity(ies) may then be filled with the same or a different bonefiller 60. These methods may be followed until all desired cavities havebeen formed and filled.

[0087] Once all desired cavities have been filled, the insertion device200 may be removed from the vertebral body 30. The incision 25 may thenbe stitched closed and/or covered with bandages.

[0088] FIGS. 31-33 depict an alternate embodiment of an insertion device600 constructed in accordance with the teachings of the presentinvention. The insertion device 600 comprises a hollow member 620 and anexpandable structure 710. A handle 615 may be provided on the distal endof the hollow member 510 to facilitate manipulation of the tool and/orintroduction of a medium to expand the expandable structure 710. Thehollow member 620, desirably having a lumen 622 extending therethrough,comprises a shaft 624 and a distal tip 625. The distal end 625 of theshaft 624 can be rounded or beveled to facilitate passage throughcortical/cancellous bone, or can be or flattened to minimizeopportunities for penetrating the opposite cortical wall of the targetedbone region. An opening or window 700 is formed in the shaft 624, withan expandable structure 710 desirably positioned within the lumen 622 ata location adjacent the window 700. Upon introduction of the insertiondevice 600 into a targeted bone region (not shown), the expandablestructure 710 can be expanded (See FIG. 33, P1 to P2 to P3), and atleast a portion of the expandable structure 710 will desirably expandthrough the window 700, thereby compressing cancellous bone, creating acavity and/or displacing cortical bone. Upon contraction of theexpandable structure 710, most of the expandable structure 710 willdesirably be drawn back into the lumen 622 for removal of the device 600from the vertebral body. If desired, the handle 615 and/or proximal end612 of the hollow member 510 can include markings (not shown) whichindicate the orientation of the window 700 within the targeted boneregion.

[0089] The expandable structure 710 may be comprised of a flexiblematerial common in medical device applications, including, but notlimited to, plastics, polyethylene, mylar, rubber, nylon, polyurethane,metals or composite materials. Desirably, the shaft 624 will comprise amaterial that is more resistant to expansion than the material of theexpandable structure 710, including, but not limited to, stainlesssteel, ceramics, composite material and/or rigid plastics. In analternate embodiment, similar materials for the expandable structure 710and shaft 624 may be used, but in different thickness and/or amounts,thereby inducing the expandable structure 710 to be more prone toexpansion than the shaft 624. The expandable structure 710 may be bondeddirectly to the shaft 624 by various means well known in the art,including, but not limited to, means such as welding, melting, gluing orthe like. In alternative embodiments, the expandable structure may besecured inside or outside of the shaft 624, or a combination thereof. Inat least one alternative embodiment, at least a portion of the materialcomprising the expandable structure 710 will plastically deform as itexpands.

[0090] If desired, the shaft 624 may be sized to pass through the lumenof a cannula or spinal access needle (not shown) already positionedwithin the targeted bone region. Alternatively, this embodiment of aninsertion device 600 can be utilized without an associated insertiondevice. In such a case, the insertion device 600 will desirablyincorporate a sharpened distal tip 625 capable of penetrating the softtissues and cortical/cancellous bone of the vertebral body. The distaltip may be hollow or a solid construct, depending upon the desiredpenetration strength of the device 600. Similarly, the window 700 mayextend around more or less of the periphery of the shaft 624, dependingupon the size and configuration of the expandable structure 710 and thedesired penetration strength of the device. For example, where thewindow 700 extends around approximately 25% of the shaft 624, thepenetration strength of the device 600 will be significantly greaterthan where the window extends around approximately 75% of the shaft 624.If desired, the handle 615 can incorporate an impacting surface (notshown) to facilitate the use of an orthopedic mallet in placing thedevice 600 in a targeted bone region. In an alternate embodiment, aftercreation of the cavity, the expandable structure can be removed from thehollow member 600, allowing bone filler to be introduced into the cavitythrough the hollow member.

[0091]FIGS. 34 through 36 depict another alternate embodiment of anexpansion guide 800 constructed in accordance with an alternateembodiment of the present invention. In this embodiment, the platform810 comprises a semi-cylindrical section which extends from the walls ofthe hollow member 820. A notch 825 extends longitudinally along theplatform 810. The notch 825 will accommodate a key or projection of anexpandable structure (not shown), desirably securing the expandablestructure to the platform 810.

[0092] Depending on the quality and strength of the surroundingcancellous and/or cortical bone, as an expandable structure expandsagainst the platform 810, the structure can “slide off” the platform810. In a similar manner, rotation of the platform may displace theexpandable structure in an unwanted manner. Desirably, the notch 825will secure the structure to the platform 810, preventing suchoccurrences. In addition, the structure may be contracted and the notch825 used to draw the expanding structure back into proper orientationwith the platform 810.

[0093]FIGS. 37 through 39 depict one method of manufacturing theplatform 810 of FIG. 34. In this embodiment, a distal end of the shaft820 is cut along a longitudinal line A. Alternatively, the shaft 820 maybe cut along longitudinal lines B, depending upon the desired size ofthe notch and the desired angles of the side walls of the notch. Theshaft is placed in a stamping machine 850 and a die 860 stamps the cutwalls 821 of the shaft 820 against the opposing walls 822 of the shaft820. Desirably, the cut walls 821 will contact the opposing walls 822,thereby forming a notch 825 between by the cut walls 821 and theopposing wall 822.

[0094] In a similar manner, a notch could be formed in the embodiment ofan insertion device described in FIGS. 29 and 30, and used to guide andsecure an expandable body to the platform. Once positioned within thetargeted bone region, the platform could be manipulated and/or rotatedwith the expandable structure secured thereto. This embodiment wouldthereby greatly facilitate proper placement of the expandable structureon the platform in a desired orientation. If desired, the notch could beformed by molding, grinding, stamping or any other machining methodknown to those in the art.

[0095] While the disclosed devices and methods are more specificallydescribed in the context of the treatment of human vertebrae, otherhuman or animal bone types can be treated in the same or equivalentfashion. By way of example, and not by limitation, the present systemsand methods could be used in any bone having bone marrow therein,including the radius, the humerus, the vertebrae, the femur, the tibiaor the calcaneous.

[0096] Other embodiments and uses of the invention will be apparent tothose skilled in the art from consideration of the specification andpractice of the invention disclosed herein. All documents referencedherein are specifically and entirely incorporated by reference. Thespecification and examples should be considered exemplary only, with thetrue scope and spirit of the invention being indicated by the followingclaims. As will be easily understood by those of ordinary skill in theart, variations and modifications of each of the disclosed embodiments,including combinations thereof, can be easily made within the scope ofthis invention as defined by the following claims.

What is claimed is:
 1. A method of directing the expansion of anexpandable structure within a bone, comprising the steps of introducingan expandable structure into the bone; introducing a substantially rigidsurface into the bone at a location adjacent the expandable structure;expanding the expandable structure within the bone.
 2. The method ofclaim 1 wherein during the expanding step the expandable structurecreates a cavity within the bone.
 3. The method of claim 1, whereinduring the expanding step the expandable structure compress at least aportion of a cancellous bone within the bone.
 4. The method of claim 1,wherein during the expansion step the expandable structure displaces atleast a portion of a cortical bone within the bone.
 5. The method ofclaim 1, wherein the expandable structure is introduced before thesubstantially rigid surface is introduced.
 6. The method of claim 1,wherein a pliable surface is positioned between the substantially rigidsurface and the expandable structure.
 7. The method of claim 1, whereinthe expandable structure directly contacts the substantially rigidsurface during the expansion step.
 8. The method of claim 1, wherein thesubstantially rigid surface resists displacement during the expansionstep.
 9. The method of claim 1, wherein the substantially rigid surfacecomprises a platform.
 10. The method of claim 1, wherein thesubstantially rigid surface is attached to the expandable structure. 11.The method of claim 1, further comprising the steps of contracting theexpandable structure and removing the structure from the bone, andintroducing a filler material into the cavity.
 12. The method of claim11, wherein the filler material comprises bone cement.
 13. The method ofclaim 1, wherein the substantially rigid surface comprises stainlesssteel.
 14. The method of claim 1, wherein the substantially rigidsurface extends along substantially the entire length of the expandablestructure.
 15. A method of treating a weakened, fractured or diseasedbone, the method comprising: introducing an insertion device through acortical bone region and into a cancellous bone region of the bone;positioning the insertion device such that a platform extending from adistal end of the insertion device is positioned between an expandabledevice and a portion of the cancellous bone region; expanding theexpandable device and creating a cavity within the bone.
 16. The methodof claim 15, further comprising filling the cavity with a bone filler.17. The method of claim 15, wherein the expandable structure isintroduced into the cancellous bone region through a lumen in theinsertion device.
 18. The method of claim 16, wherein the bone fillercomprises bone cement.
 19. A device for directing the expansion of anexpandable structure, the device comprising: a member having a proximaland a distal end and a lumen extending therethrough; a platformextending adjacent the distal end.
 20. The device of claim 19 whereinthe platform comprises stainless steel.
 21. The device of claim 19,further comprising an expandable structure substantially secured to themember, the expandable structure located substantially within the lumen.